Two-dimensional networks of ethylenedithiotetrathiafulvalene derivatives with the hydrogen-bonded functionality of uracil, and channel structure of its tetracyanoquinodimethane complex

Article abstract of DOI:10.1021/jo060748l

Ethylenedithiotetrathiafulvalene (EDT-TTF) derivatives with N ¹-butyluracil or N¹-phenyluracil moiety were designed and synthesized as new hydrogen-bonded electron-donor molecules with the aim of introducing multiple S...S interactio

Full text of DOI:10.1021/jo060748l

Two-Dimensional Networks of Ethylenedithiotetrathiafulvalene
Derivatives with the Hydrogen-Bonded Functionality of Uracil, and
Channel Structure of Its Tetracyanoquinodimethane Complex
Yasushi Morita,*,†,‡ Eigo Miyazaki,† Yoshikazu Umemoto,† Kozo Fukui,‡ and
Kazuhiro Nakasuji*,†
Department of Chemistry, Graduate School of Science, Osaka UniVersity, Toyonaka, Osaka, 560-0043,
Japan, and PRESTO, Japan Science and Technology Agency (JST),
Hon-cho, Kawaguchi, Saitama, 332-0012, Japan
morita@chem.sci.osaka-u.ac.jp
ReceiVed April 10, 2006
Ethylenedithiotetrathiafulvalene (EDT-TTF) derivatives with N1-butyluracil or N1-phenyluracil moiety
were designed and synthesized as new hydrogen-bonded electron-donor molecules with the aim of
introducing multiple S‚‚‚S interactions into the hydrogen-bonded structures composed of the TTF-
nucleobase systems. In the crystals of the EDT-TTF derivatives, two-dimensional sheet and layer structures
were formed through π‚‚‚π, multiple S‚‚‚S interactions, and complementary double hydrogen bonds. In
the tetracyanoquinodimethane (TCNQ) charge-transfer complex of the EDT-TTF-N1-butyluracil dyad
with a segregated column, a layer structure of the electron-donor molecules was constructed through the
noncovalent interactions. The n-butyl group of the uracil moiety served to separate the space between
the donor layers, resulting in construction of a channel structure. Disordered TCNQ molecules were
located in the microporous space of the channel. The TCNQ complex exhibited high electric conductivity
(σrt ) 2.1 S cm-1) in a single crystal.
Introduction
of the directional and strong hydrogen-bonding (H-bonding)
interactions2 such as NH‚‚‚N and OH‚‚‚O is one of the hot topics
in the studies of organic conductors.3 In addition to such a
structural effect of the H-bond, we recently demonstrated new
roles of the H-bonding interaction: control of electron-donating
and -accepting abilities of donor/acceptor molecules and their
molecular ratio in the CT complexes of the dibenzo-TTF
Organic charge-transfer (CT) complexes and salts based on
tetrathiafulvalene (TTF) and its derivatives were widely inves-
tigated in the field of molecule-based conductive materials
science.1 From the viewpoint of crystal engineering, utilization
* To whom correspondence should be addressed. Phone: +81-6-6850-5393.
Fax: +81-6-6850-5395.
† Osaka University.
(2) Recent reviews of H-bonding, see: (a) An Introduction to Hydrogen
Bonding; Jeffrey, G. A., Ed.; Oxford University Press: New York, 1997.
(b) The Weak Hydrogen Bond; Desiraju, G. R., Steiner, T., Eds.; Oxford
University Press: New York, 1999; Chapter 1.
(3) Recent overview on structures and properties of TTF derivatives with
H-bonding functionalities, see: Fourmigue´, M.; Batail, P. Chem. ReV. 2004,
104, 5379.
‡ PREST, JST.
(1) Recent overviews on organic conductors, see: (a) Organic Super-
conductors, 2nd ed.; Ishiguro, T., Yamaji, K., Saito, G., Eds.; Springer-
Velrag: Tokyo, 1998. (b) TTF Chemistry: Fundamentals and Applications
of TetrathiafulValene; Yamada, J., Sugimoto, T., Eds.; Kodansha and
Springer: Tokyo, 2004.
10.1021/jo060748l CCC: $33.50 © 2006 American Chemical Society
Published on Web 06/27/2006
J. Org. Chem. 2006, 71, 5631-5637
5631

Morita et al.
derivative with amino groups4 and the TTF derivative with
imidazole systems.5 As part of our ongoing studies, we
investigated TTF π-systems with nucleobases such as uracil and
N1-butyluracil, TU and TnbU,6 and established the usefulness
of the introduction of nucleobases into the TTF π-system to
construct highly ordered multidimensional molecular systems
based on complementary double H-bonds.7 Notably, achieve-
ment of high electrical conductivities in the tetracyanoquino-
dimethane (TCNQ) CT complexes of TU and TnbU showed
an interesting strategy for the construction of H-bonded CT
complexes.6 These stimulative results have encouraged us to
study further TTF derivatives with nucleobases.
Chemical modification of the TTF moiety also gives a good
opportunity to acquire molecule-based conductive materials with
multidimensional networks. It is well-known that the ethylene-
dithio group of ethylenedithiotetrathiafulvalene (EDT-TTF) can
contribute to the formation of a multidimensional network
structure by intermolecular interactions through several sulfur
atoms.1 Importantly, in the CT salts of EDT-TTF derivatives
with H-bonding functionalities, the intermolecular S‚‚‚S interac-
tions played a key role in realizing highly conductive H-bonded
materials having multidimensional structures with the help of
H-bonds.8,9 Thus, we have newly designed EDT-TTF derivatives
with N1-butyluracil and N1-phenyluracil moieties, 1a and 1b,
FIGURE 1. Cyclic voltammograms measured in DMF for 1a (a), 1b
(b), and EDT-TTF (c). For conditions see the Experimental Section.
SCHEME 1. Synthetic Methods for 1a and 1b
respectively, so as to introduce multiple S‚‚‚S interactions into
H-bonded structures composed of TTF-nucleobase systems.
Here we report on the syntheses, structures, and physical
properties of 1a, 1b, and their TCNQ CT complexes, revealing
two-dimensional networks for 1a and 1b, and a channel structure
for (1a)2-TCNQ with high electric conductivity (σrt ) 2.1 S
cm-1) in a single crystal.
n-butyl and phenyl groups, 4a and 4b, were prepared from 2a6
and 2b10 by iodination and protection of NH groups. Coupling
reactions between 4a, 4b, and the tributyltin derivative of EDT-
TTF (EDT-TTF-SnBu3) produced benzoyl-protected derivatives,
5a and 5b. EDT-TTF derivatives, 1a and 1b, were synthesized
by removal of the benzoyl group of 5a and 5b in 29% and 22%
yield in three steps form EDT-TTF, respectively. We have found
that the benzoyl group facilitates easy purification and enlarge-
ment of reaction scale for 5a and 5b because of an increase of
the solubility for common organic solvents such as CH2Cl2 and
THF. Furthermore, our present coupling reaction condition in
the presence of CuI and P(o-tolyl)3 improved the reaction yield
compared with that of our previous method for TU and TnbU.11
The CT complexes of 1a and 1b with TCNQ were obtained as
black powders by mixing both CH2Cl2 solutions. Molecular
ratios of the TCNQ complexes were found to be 2:1 (D:A) and
2:1:1 (D:A:H2O), and these complexes are formulated as (1a)2-
TCNQ and (1b)2-TCNQ‚H2O, respectively.
Results and Discussion
Synthesis. Synthetic methods for 1a and 1b were illustrated
in Scheme 1. Benzoyl-protected 5-iodouracil derivatives with
(4) Morita, Y.; Miyazaki, E.; Fukui, K.; Maki, S.; Nakasuji, K. Bull.
Chem. Soc. Jpn. 2005, 78, 2014.
(5) Murata, T.; Morita, Y.; Fukui, K.; Sato, K.; Shiomi, D.; Takui, T.;
Maesato, M.; Yamochi, H.; Saito, G.; Nakasuji, K. Angew. Chem., Int. Ed.
2004, 43, 6343.
(6) Morita, Y.; Maki, S.; Ohmoto, M.; Kitagawa, H.; Okubo, T.; Mitani,
T.; Nakasuji, K. Org. Lett. 2002, 4, 2185.
(7) As an alternative approach for utilization of nucleobases in the TTF
π-system, uracil- and cytosine-fused TTF derivatives are reported. The
betaine compounds of these systems exhibited high electrical conductivities
as single-component molecular conductors. However, poor solubilities
hamper clarification of the crystal structures. See: (a) Neilands, O.;
Belyakov, S.; Tilika, V.; Edzina, A. J. Chem. Soc., Chem. Commun. 1995,
325. (b) Neilands, O. Y.; Tilika, V.; Sudmale, I.; Grigorjeva, I.; Edzina,
A.; Fonavs, E.; Muzikante, I. AdV. Mater. Opt. Electron. 1997, 7, 39. (c)
Balodis, K.; Khasanov, S.; Chong, C.; Maesato, M.; Yamochi, H.; Saito,
G.; Neilands, O. Synth. Met. 2003, 133-134, 353.
(8) Several H-bonded CT salts of EDT-TTF-CONHR (R ) H, Me) with
metallic behavior were reported. See: (a) Heuze´, K.; Fourmigue´, M.; Batail,
P.; Canadell, E.; Auban-Senzier, P. Chem. Eur. J. 1999, 5, 2971. (b) Heuze´,
K.; Me´zie`re, C.; Fourmigue´, M.; Batail, P.; Coulon, C.; Canadell, E.; Auban-
Senzier, P.; Je´rome, D. Chem. Mater. 2000, 12, 1898.
Electron-Donating Ability. The cyclic voltammograms of
1a and 1b in DMF exhibit two-stage reversible oxidation waves
(Figure 1). Slightly negative shifts of the first oxidation
potentials of 1a and 1b by 0.01-0.02 V were observed
(10) Naim, A.; Shevlin, P. B. Synth. Commun. 1990, 60, 554.
(11) Previous coupling condition for TU and TnbU with EDT-TTF-SnBu3
and 4a and 4b gave 1a and 1b in 20% and 10% yields in three steps,
respectively. See ref 6.
(9) Ono, G.; Terao, H.; Higuchi, S.; Sugawara, T.; Izuoka, A.; Mochida,
T. J. Mater. Chem. 2000, 10, 2277.
5632 J. Org. Chem., Vol. 71, No. 15, 2006

EthylenedithiotetrathiafulValene with Uracil
TABLE 1. Half-Wave Oxidation Potentials for 1a, 1b, and
EDT-TTFa
ox1
ox2
E1/2
E1/2
∆E
1a
1b
EDT-TTF
+0.00
+0.01
+0.02
+0.18
+0.19
+0.21
0.18
0.18
0.19
a Fc/Fc+ ) 0 V. For conditions, see the Experimental Section.
FIGURE 3. Crystal structure of 1b: chain structure through Watson-
Crick type complementary double H-bonds (light blue line) and S‚‚‚S
interaction (greenish yellow line) with the S‚‚‚S distances of 3.38 Å
between the TTF moieties (a) and the two-dimensional layer structure
through H-bonding, S‚‚‚S and π‚‚‚π interactions with an interplanar
distance of 3.38 Å along the b-axis (b). Hydrogen atoms are omitted
for clarity.
within the sum of van der Waals radii (3.60 Å)12 are observed
between not only the TTF moieties (3.48 Å) but also the
ethylenedithio moieties (3.50 Å). Collaboration of these comple-
mentary double H-bonds and multiple S‚‚‚S interactions con-
structs a two-dimensional sheet structure. Additionally, TTF and
uracil moieties are partially overlapped through the π‚‚‚π
interaction with a distance of 3.53 Å (Figure 2b).
Single crystals of 1b crystallized in a monoclinic system,
space group C2/c, were also obtained by the vapor diffusion
method with use of DMF-water. Dihedral angles between EDT-
TTF and uracil and those between the uracil moiety and the
phenyl group are 11.6(2)° and 115.2(3)°, respectively. In the
uracil moiety, an H-bonded dimer connected with Watson-
Crick type complementary double H-bonds with an NH‚‚‚O
distance of 2.86 Å is formed (Figure 3a). There is a strong S‚
‚‚S interaction of 3.38 Å between the TTF moieties. Further-
more, the regular stacking structure is formed through the π‚‚
‚π interaction of an interplanar distance of 3.38 Å with partial
overlap between TTF and uracil moieties, resulting in formation
of a two-dimensional layer structure (Figure 3b).
FIGURE 2. Crystal structure of 1a: two-dimensional sheet structure
through Watson-Crick type complementary double H-bonds (blue line)
and multiple S‚‚‚S interactions (greenish yellow line) with the S‚‚‚S
distances of 3.48 and 3.50 Å between TTF moieties and ethylenedithio
moieties, respectively (a). The light colored molecular network denotes
the sheet of the backward network (b). Hydrogen atoms are omitted
for clarity.
compared with that of EDT-TTF, indicating that 1a and 1b
possess sufficient electron-donating abilities for forming the CT
complexes with common organic acceptors (Table 1). Consider-
ing approximately the same ∆E values of 1a, 1b, and EDT-
TTF, the degree of their on-site coulomb repulsion is practically
the same.
Crystal Structures of 1a and 1b. Single crystals of 1a
suitable for an X-ray structure analysis were obtained as red
blocks by the vapor diffusion method with use of DMF-water,
and 1a crystallizes in a triclinic system, space group P1h. The
dihedral angle between the EDT-TTF and uracil moieties is
2.82(7)°. Watson-Crick type complementary double H-bonds
through C4dO‚‚‚HsN3 in the uracil moieties are formed, in
which the closest double NH‚‚‚O contacts are 2.81 Å (Figure
2a). Furthermore, multiple intermolecular short S‚‚‚S interactions
Crystal Structure of (1a)2-TCNQ. Single crystals of (1a)2-
TCNQ were obtained by slow evaporation, using its CH2Cl2
solution. The dihedral angle between EDT-TTF and uracil
(12) Bondi, A. J. Phys. Chem. 1964, 68, 441.
J. Org. Chem, Vol. 71, No. 15, 2006 5633

Morita et al.
FIGURE 4. Crystal structure of (1a)2-TCNQ: overlap modes of 1a and TCNQ (a, b), one-dimensional chain structure through multiple S‚‚‚S
contacts (greenish yellow line) and Watson-Crick type complementary double H-bonds (blue line) (c), and channel structure constructed by 1a (d).
Hydrogen atoms are omitted for clarity.
moieties is 7.2(2)°. In this TCNQ complex, the segregated
stacking structure is formed (Figure 4a,b). Watson-Crick type
complementary double H-bonds through C4dO‚‚‚HsN3 in the
uracil moieties are formed (NH‚‚‚O distance: 2.80 Å, see Figure
4c). This H-bonded motif in the uracil moiety is also the same
as that of 1a.13 These H-bonding natures observed only between
electron-donor molecules are rare events as the CT complexes
and salts of the TTF derivatives with H-bonded functionality.14
As expected, there are intermolecular multiple S‚‚‚S contacts
(3.38 and 3.42 Å) between EDT-TTF moieties in the side-by-
side direction. In addition to these noncovalent interactions, π‚
‚‚π interaction with an interplanar distance of 3.46 Å is observed
between the donor molecules, resulting in construction of the
two-dimensional layer structure. The n-butyl group of the uracil
moiety serves to separate the space between the columns and
to construct a channel structure (Figure 4d). The functional
FIGURE 5. Infrared spectra of 1a (a), 1b (b), (1a)2-TCNQ (c), (1b)2-
TCNQ‚H2O (d), TnbU (e), and TnbU-TCNQ (f) in KBr pellets.
channel structure was often shown in the CT salts of TTF
derivatives with a metal complex.15 TCNQ molecules are located
in the microporous space of the channel structure. Due to
disorder of TCNQ molecules along the stacking direction in
the channel, the existence of intermolecular S‚‚‚N interaction
between the donor and the TCNQ molecule is unclear.16 From
the data of the X-ray structure analysis, reflections due to the
supercell were not observed in this TCNQ complex.
Optical Properties of TCNQ Complexes of 1a and 1b. The
H-bonded motif in the 3,4-positions of the uracil moiety
observed by the X-ray crystal structure analyses of 1a, 1b, and
(1a)2-TCNQ is also confirmed by IR spectra in the region of
carbonyl stretching frequencies of 1500-1800 cm-1 (Figure
5).17 Two absorption bands at 1661-1674 and 1698-1710 cm-1
are assignable to 4- and 2-positions of the uracil moiety,
respectively. The carbonyl stretching frequencies of the (1b)2-
TCNQ‚H2O are also observed at 1676 and 1710 cm-1, which
(13) In the TTF-uracil system, transformation of complementary double
hydrogen-bonding motifs from Watson-Crick type to revese Watson-Crick
type by redox change of the TTF moiety was reported. See: Miyazaki, E.;
Morita, Y.; Umemoto, Y.; Fukui, K.; Nakasuji, K. Chem. Lett. 2005, 34,
1326.
(14) In general, H-bonds tend to form between electron donor and
acceptor/counterion/crystal solvent in H-bonded TTF systems. See ref 3.
(15) In {(TTF)2[Fe(CA)2(H2O)2]}n (H2CA ) chloranilic acid), TTF
molecules were included in the channel. See: (a) Nagayoshi, K.; Kabir M.
K.; Tobita, H.; Honda, K.; Kawahara, M.; Katada, M.; Adachi, K.;
Nishikawa, H.; Ikemoto, I.; Kumagai, H.; Hosokoshi, Y.; Inoue, K.;
Kitagawa, S.; Kawata, S. J. Am. Chem. Soc. 2003, 125, 221. Also disordered
+
H3O+/NH4 molecules capable of proton conducting were located in the
channel formed by the stack of crown ether in (BEDT-TTF)4[(Cat)MIII-
(C2O4)3]2([18]crown-6-ether)]‚5H2O (BEDT-TTF ) bis(ethylenedithio)-
tetrathiafulvalene, Cat ) H3O+ or NH4+). See: (b) Rashid, S.; Turner, S.
S.; Day, P.; Light, M. E.; Hursthouse, M. B.; Firth, S.; Clark, R. J. H.
Chem. Commun. 2001, 1462. (c) Akutsu-Sato, A.; Akutsu, H.; Turner, S.
S.; Day, P.; Probert, M. R.; Howard, J. A. K.; Akutagawa, T.; Takeda, S.;
Nakamura, T.; Mori, T. Angew. Chem., Int. Ed. 2005, 44, 292.
(16) The S‚‚‚N distance between TCNQ and 1a obtained by X-ray crystal
structure analysis gave 3.03 Å, which is shorter than that of the sum of van
der Waals radii (3.35 Å).
(17) We have already discussed the relationship between H-bonded motifs
and carbonyl stretching frequencies in the TTF-uracil system. See ref 6.
5634 J. Org. Chem., Vol. 71, No. 15, 2006

EthylenedithiotetrathiafulValene with Uracil
TABLE 2. Selected Physical Properties for TCNQ Complexes of
1a and 1b
CN
stretching,
cm-1
ionicity
of
CT
band,
σrt,
Ea,
meV
TCNQa cm-1
S cm-1
(1a)2-TCNQ
(1b)2-TCNQ‚H2O
2193
2195
0.77
0.73
4500 2.1b
72
61
3000d 6.4 × 10-3 c
a Ionicity of the TCNQ molecule was estimated by the CN stretching
frequency of the IR spectrum on the basis of Chappell’s method. See ref
18. b Electric conductivity of a single crystal was measured by a two-probe
method. c Electric conductivity of a compressed pellet was measured by a
four-probe method. d See ref 19.
FIGURE 7. Temperature-dependent conductivities for (1a)2-TCNQ
(a) and (1a)2-TCNQ‚H2O (b) measured by using a single crystal and
a compressed pellet, respectively.
conductivities despite the H-bonded CT complexes.22 Room
temperature electric conductivities (σrt) and activation energies
(Ea) measured by a single crystal and a compressed pellet are
determined to be 2.1 S cm-1 and 72 meV for (1a)2-TCNQ
and 6.4 × 10-3 S cm-1 and 61 meV for (1b)2-TCNQ‚H2O,
respectively (Table 2 and Figure 7). Especially, the σrt value of
(1a)2-TCNQ is three orders higher than that of the TCNQF4
complex of EDT-TTF-CONH2 with partial CT state.23 This
result of (1a)2-TCNQ is in accord with the segregated stacking
structure and partial CT states of donor and acceptor molecules
(vide supra). Especially, multiple S‚‚‚S interactions between the
EDT-TTF moieties, playing an important role in forming the
channel structure, may contribute to high electric conductivity.
FIGURE 6. Electronic spectra of 1a (a), 1b (b), (1a)2-TCNQ (c),
and (1b)2-TCNQ‚H2O (d) in KBr pellets.
are similar values compared with those of 1a, 1b, and (1a)2-
TCNQ. This result indicates that in (1b)2-TCNQ‚H2O the
formation of Watson-Crick type complementary double H-
bonds between the donor molecules is expected as seen in
(1a)2-TCNQ.
Ionicities of TCNQ molecules were estimated to be 0.77 for
(1a)2-TCNQ and 0.73 for (1b)2-TCNQ‚H2O in terms of the
nitrile stretching frequencies of the B1u mode of the IR spectra
(Table 2).18 Considering the molecular ratio of donor and
acceptor, the ionicities of 1a and 1b in the TCNQ complexes
are 0.39 and 0.37, respectively.
In the electronic spectra of (1a)2-TCNQ and (1b)2-TCNQ‚
H2O in KBr pellets, low-energy bands were observed around
4500 and 3000 cm-1, respectively, which is assignable to
intrastack CT transition due to the donor and/or acceptor column
(Figure 6).19 The identification of the absorption band around
12 000-14 000 cm-1, however, is less clear. Several possibilities
of its origin can be considered: intramolecular transition due
to radical anionic species of TCNQ; intermolecular CT transition
due to the dimer of the TCNQ molecules; and intermolecular
CT transition due to the dimer of the donor molecules.20,21
Electric Conductivities of TCNQ Complexes. These TCNQ
complexes exhibited semiconductive behaviors with high electric
Conclusions
The crystal structures of 1a and 1b demonstrated that the
utilization of ethylenedithio-functionalized TTF was an effective
way to introduce multiple S‚‚‚S interactions between donor
molecules even in an H-bonded CT system, resulting in
construction of a two-dimensional network. Notably, this study
has succeeded in solving the first crystal structure of the TCNQ
CT complex of the TTF-nucleobase system, (1a)2-TCNQ,
showing the interplay of complementary double H-bonds, π‚‚
‚π, and multiple S‚‚‚S interactions. These features highly
contributed to the construction of the layer structure of electron-
donor molecules. Furthermore, a key feature of a purely organic
system in the structural motif of the (1a)2-TCNQ CT complex
includes the channel structure containing partially ionized TCNQ
columns to show high electric conductivity (σrt ) 2.1 S cm-1).24
Interestingly, the uracil moiety serve to form the H-bonded
dimer of electron-donor molecules through the Watson-Crick
(21) The B bands of the CT process due to the intradimer of the donors
in TTF and BEDT-TTF are approximately 14 000 and 10 000 cm-1
.
Therefore, that of expectable values in EDT-TTF is 12 000 cm-1. See ref
14 and the following: Lapi’nski, A.; Graja, A.; Prokhorova, T. G. J. Mol.
Struct. 2004, 704, 83.
(18) (a) Chappell, J. S.; Bloch, A. N.; Bryden, W. A.; Maxfield, M.;
Poehler, T. O.; Cowan, D. O. J. Am. Chem. Soc. 1981, 103, 2442. It is
noteworthy that an estimation of ionicity of the TCNQ molecule by
Chappell’s method remains ambiguous, because it often gives inaccurate
values in larger ionicity than ∼0.5. See: (b) Saito, G.; Hirate, S.; Nishimura,
K.; Yamochi, H. J. Mater. Chem. 2001, 11, 723. (c) Pac, S.-S.; Saito, G. J.
Solid State Chem. 2002, 168, 486.
(22) In a variety of H-bonded CT complexes and salts based on the TTF
derivatives, most of them exhibited semiconductive behavior with low
conductivity below 10-5 S cm-1 or are insulators except for several
examples. See refs 3, 5, 8, and 9.
(23) Partial CT complex of (EDT-TTF-CONH2)2-TCNQF4 with the one-
dimensional chain of the electron-donor molecule exhibiting a relatively
high conductivity of 3 × 10-3 S cm-1 (σrt) in a single crystal. See: Baudron,
S. A.; Me´zie`re, C.; Heuze´, K.; Fourmigue´, M.; Batail, P.; Molinie´, P.;
Auban-Senzier, P. J. Solid State Chem. 2002, 168, 668.
(19) A CT band of (1b)2-TCNQ‚H2O was observed around 3000 cm-1
in the IR spectra in KBr pellet. However, this assignment is obscure because
of the possibility for overlap of the absorption of water. See IR spectra in
the Supporting Information.
(20) Torrance, J. B.; Scott, B. A.; Welber, B.; Kaufman, F. B.; Seiden,
P. E. Phys. ReV. 1979, B19, 730.
(24) For a recent review on functional metal coordination polymers with
channel structures, see: Kitagawa, S.; Kitaura, R.; Noro, S. Angew. Chem.,
Int. Ed. 2004, 43, 2334.
J. Org. Chem, Vol. 71, No. 15, 2006 5635

Morita et al.
mmol) was placed in a 100-mL Schlenk tube and dissolved with
THF (22 mL). After the solution was cooled at -78 °C, n-BuLi
(1.6 M hexane solution, 0.63 mL, 1.0 mmol) was added and the
mixture was stirred at -78 °C for 1 h. To this mixture was added
tributyltin(IV) chloride (0.29 mL, 1.0 mmol), and the solution was
gradually warmed to room temperature. After being stirred for 30
min, a pH 7.0 phosphate buffer solution (0.1 M, 25 mL) was poured,
and the reaction mixture was extracted with ethyl acetate (2 × 30
mL). The combined organic extracts were dried over anhydrous
Na2SO4, then filtered and concentrated under reduced pressure to
give the mixture of tributyltin-substituted EDT-TTF (written simply
as EDT-TTF-SnBu3) and EDT-TTF (766 mg) as a red oil. This
crude oil was used for the next coupling reactions.
The mixture of EDT-TTF-SnBu3 and EDT-TTF (766 mg), 4a
(404 mg, 1.0 mmol), copper(I) iodide (58 mg, 0.30 mmol), and
tris(o-tolyl)phosphine (96 mg, 0.30 mmol) were placed in a 50-
mL Schlenk tube and dissolved in THF (15 mL). To this mixture
was added tetrakis(triphenylphosphine)palladium(0) (117 mg, 0.10
mmol), and the solution was stirred at room temperature for 27 h.
After quenching by the addition of water (30 mL), the solution
was extracted with ethyl acetate (2 × 40 mL). The combined
organic extracts were dried over anhydrous Na2SO4, then filtered
and concentrated under reduced pressure. The residual powder was
purified by silica gel column chromatography with 5:1 hexanes-
ethyl acetate and ethyl acetate, to give a mixture of the EDT-TTF
derivative with benzoyl-protected butyluracil 5a and 4a (516 mg).
5a: TLC Rf 0.58 (1:1 hexane/ethyl acetate).
type complementary double N-H‚‚‚O H-bonds in all EDT-TTF
derivatives independent of substituent on uracil and the redox
nature of the molecule. Construction of multidimensional
networks through noncovalent interactions and achievement of
high electric conductivity in the H-bonded CT complex will
bring us the beginning of the elucidation and realization of the
cooperative proton and electron-transfer process.25
Experimental Section26
5-Iodo-N1-phenyluracil (3b). N1-Phenyluracil10 (2.5 g, 13 mmol)
was placed in a Schlenk tube equipped with a reflux condenser
and dissolved with CH2Cl2 (15 mL). To this mixture was added
iodine chloride (1.4 mL, 27 mmol) and the mixture was refluxed
for 1 h. After the solution was cooled at room temperature, the
resulting white precipitate was collected by filtration and washed
with ether. This residue was recrystallized from ethyl acetate-
ethanol (1:1) to give 5-iodo-N1-phenyluracil (3.3 g, 77%) as a white
solid: mp 285-286 °C; TLC Rf 0.64 (ethyl acetate); 1H NMR (270
MHz, DMSO-d6) δ 7.44 (m, 5H), 8.18 (s, 1H), 11.8 (br s, 1H); IR
(KBr) 3165, 3050, 1701, 1675 cm-1; EI-MS, m/z 314 (M+, 47%).
Anal. Calcd for C10H7N2O2I: C, 38.24; H, 2.25; N, 8.92. Found:
C, 37.97; H, 2.17; N, 8.83.
N3-Benzoyl-N1-n-butyl-5-iodouracil (4a). N1-n-Butyl-5-iodor-
acil6 (5.0 g, 17 mmol) was placed in a 100-mL round-bottomed
flask and dissolved in CH3CN (17 mL) and pyridine (7 mL)
following addition of benzoyl chloride (4.3 mL, 37 mmol) at room
temperature. After the solution was stirred at room temperature for
24 h, the solvents were removed by evaporation, and ethyl acetate
(300 mL) and water (100 m) were added. The organic layer was
separated and washed with water (100 mL), dried over anhydrous
Na2SO4, filtered, and concentrated under reduced pressure. The
residual yellow oil was recrystallized from hexanes-ethyl acetate
to give 4a (6.5 g, 96%) as a white solid. Mp 129-130 °C; TLC Rf
0.63 (1:1 hexane/ethyl acetate); 1H NMR (270 MHz, DMSO-d6) δ
0.88 (t, 3, J ) 7.3 Hz), 1.21-1.35 (m, 2), 1.55-1.66 (m, 2), 3.73
(t, 2, J ) 7.4 Hz), 7.56-7.62 (m, 2), 7.75-7.81 (m, 1), 7.95-7.99
(m, 2), 8.45 (s, 1); IR (KBr) 3074, 1743, 1694, 1662 cm-1; FAB-
MS, m/z 399 (M + H+). Anal. Calcd for C15H15N2O3I: C, 45.24;
H, 3.80; N, 7.04. Found: C, 45.24; H, 3.62; N, 7.11.
The mixture of 5a and 4a (516 mg) was placed in a 20-mL
Schlenk tube, dispersed in 30% methylamine methanol solution (6
mL), and stirred at room temperature for 30 min. After being cooled
at 0 °C, the solution was neutralized by concentrated acetic acid
and collected, to give 1a (137 mg) as a reddish orange powder in
29% yield in three steps from EDT-TTF. Mp 240-241 °C dec;
1
TLC Rf 0.60 (ethyl acetate); H NMR (270 MHz, DMSO-d6) δ
0.90 (t, 3, J ) 7.3 Hz), 1.21-1.32 (m, 2), 1.52-1.63 (m, 2), 3.40
(s, 4), 3.73 (t, 2, J ) 7.1 Hz), 7.34 (s, 1), 7.87 (s, 1), 11.6 (br s, 1);
IR (KBr) 3415, 2954, 1703, 1661 cm-1; UV (KBr) 308, 416 nm;
EI-MS m/z 460 (M+, 71%). Anal. Calcd for C16H16N2O2S6: C,
41.71; H, 3.50; N, 6.08. Found: C, 41.59; H, 3.42; N, 5.97.
2-{4-(N1’-Phenyluracil-5’-yl)-1,3-dithile-2-ylidene}-5,6-dihy-
dro-1,3-dithiolo[4,5-b][1,4]dithiin (1b). EDT-TTF27 (100 mg, 0.34
mmol) was placed in a 100-mL Schlenk tube and dissolved in THF
(8 mL). After the mixture was cooled at -78 °C, n-BuLi (1.6 M
hexane solution, 0.21 mL, 0.34 mmol) was added and the solution
was at -78 °C for 1 h. To this mixture was added tributyltin(IV)
chloride (0.09 mL, 0.34 mmol), and the solution was gradually
warmed to room temperature. After the solution was stirred for 30
min, a pH 7.0 phosphate buffer solution (0.1 M, 15 mL) was added,
and the reaction mixture was extracted with ethyl acetate (2 × 30
mL). The combined organic extracts were dried over anhydrous
Na2SO4, then filtered and concentrated under reduced pressure, to
give a mixture of EDT-TTF-SnBu3 and EDT-TTF (255 mg) as a
red oil. This crude oil was used for the next coupling reactions.
The mixture of EDT-TTF-SnBu3 and EDT-TTF (255 mg), 4b
(141 mg, 0.34 mmol), copper(I) iodide (19 mg, 0.10 mmol), and
tris(o-tolyl)phosphine (32 mg, 0.10 mmol) were placed in a 20-
mL Schlenk tube and dissolved with THF (5 mL). To this mixture
was added tetrakis(triphenylphosphine)palladium(0) (39 mg, 0.034
mmol), and the solution was stirred at room temperature for 22 h.
After quenching by the addition of water (20 mL), the solution
was extracted with ethyl acetate (2 × 30 mL). The combined
organic extracts were dried over anhydrous Na2SO4, then filtered
and concentrated under reduced pressure. The residual powder was
purified by silica gel column chromatography with 5:1 hexanes-
ethyl acetate and ethyl acetate, to give the mixture of EDT-TTF
derivative with benzoyl-protected phenyluracil 5b and 4b (165 mg).
5b: TLC Rf 0.63 (1:1 hexane/ethyl acetate).
N3-Benzoyl-N1-phenyl-5-iodouracil (4b). 5-Iodo-N1-phenylu-
racil (5.1 g, 16 mmol) was placed in a 100-mL round-bottomed
flask and dissolved in CH3CN (20 mL) and pyridine (7 mL)
following addition of benzoyl chloride (4.2 mL, 36 mmol) at room
temperature. After being stirred at room temperature for 24 h, the
solvents were removed by evaporation and ethyl acetate (300 mL)
and water (100 m) were added. The organic layer was separated
and washed with water (100 mL) and dried over anhydrous Na2-
SO4, filtered, and concentrated under reduced pressure. The residual
white solid was recrystallized from hexanes-ethyl acetate, to give
4b (4.8 g, 69%) as a white solid. Mp 216-218 °C; TLC Rf 0.63
(1:1 hexane/ethyl acetate); 1H NMR (270 MHz, DMSO-d6) δ 7.35-
7.42 (m, 2), 7.44-7.54 (m, 5), 7.63-7.69 (m, 1), 7.91 (s, 1), 7.94-
7.99 (m, 2); IR (KBr) 3075, 1743, 1695, 1666 cm-1; FAB-MS,
m/z 419 (M+ + H). Anal. Calcd for C17H11N2O3I: C, 48.83; H,
2.65; N, 6.70. Found: C, 49.09; H, 2.56; N, 6.69.
2-{4-(N1’-n-Butyluracil-5’-yl)-1,3-dithile-2-ylidene}-5,6-dihy-
dro-1,3-dithiolo[4,5-b][1,4]dithiin (1a). EDT-TTF27 (300 mg, 1.0
(25) Nakasuji, K.; Sugiura, K.; Kitagawa, T.; Toyoda, J.; Okamoto, H.;
Okaniwa, K.; Mitani, T.; Yamamoto, H.; Murata, I.; Kawamoto, A.; Tanaka,
J. J. Am. Chem. Soc. 1991, 113, 1862-1864.
(26) See the Experimental Section in the Supporting Information for
X-ray crystal structure analyses.
(27) (a) Papavassiliou, G. C.; Mousdis, G. A.; Yiannopoulos, S. Y.;
Kakoussis, V. C.; Zambounnis, J. S. Synth. Met. 1998, 27, B373. (b)
Papavassilou, G. C.; Kakoussis, V. C.; Mousdis, G. A.; Gionis, V.;
Yiannnopoulos, S. Y. Mol. Cryst. Liq. Cryst. Incorporating Nonlinear Opt.
1998, 156, 269.
The mixture of 5b and 4b (165 mg) was placed in a 20-mL
Schlenk tube, dispersed in 30% methylamine methanol solution (2
5636 J. Org. Chem., Vol. 71, No. 15, 2006

EthylenedithiotetrathiafulValene with Uracil
mL), and stirred at room temperature for 30 min. After being cooled
at 0 °C, the solution was neutralized by concentrated acetic acid
and collected, to give 1b (36 mg) as a reddish orange powder in
22% yield in three steps from EDT-TTF. Mp 246-248 °C dec;
TLC Rf 0.30 (1:1 hexane/ethyl acetate); 1H NMR (270 MHz,
DMSO-d6) δ 3.38 (s, 4), 7.35 (s, 1), 7.41-7.53 (m, 5), 7.82 (s, 1),
11.8 (br s, 1); IR (KBr) 2842, 1710, 1674 cm-1; UV (KBr) 304,
426 nm; EI-MS m/z 480 (M+, 18%). Anal. Calcd for C18H12-
N2O2S6: C, 44.97; H, 2.52; N, 5.83. Found: C, 44.88; H, 2.63; N,
5.95.
(1a)2-TCNQ Complex. Both a CH2Cl2 solution (30 mL) of 1a
(17.5 mg, 0.038 mmol) and a CH2Cl2 solution (10 mL) of TCNQ
(7.3 mg, 0.036 mmol) were combined in a 100-mL round-bottomed
flask at room temperature, then concentrated under reduced pressure.
Residual powder was suspended in a small amount of CH3CN and
collected, to give the (1a)2-TCNQ complex (7.1 mg) as a black
powder. Mp 215-217 °C dec; IR (KBr) 2212, 2193, 2180, 1698
cm-1; UV (KBr) 300, 386, 768, 838 nm. Anal. Calcd for
(C16H16N2O2S6)2(C12H4N4): C, 46.95; H, 3.22; N, 9.95. Found. C,
46.65; H, 3.14; N, 9.83.
flask at room temperature, then concentrated under reduced pressure.
Precipitates were collected, to give the (1b)2-TCNQ‚H2O complex
(27 mg) as a black powder. Mp 269-271 °C dec; IR (KBr) 2214,
2195, 2178, 2154, 1710, 1676 cm-1; UV (KBr) 306, 774, 856 nm.
Anal. Calcd for (C18H12N2O2S6)2(C12H4N4)(H2O): C, 48.71; H,
2.55; N, 9.47. Found: C, 48.83; H, 2.61; N, 9.14. The composition
of this TCNQ complex was solely determined by the elemental
analysis.
Acknowledgment. This work was partially supported by
PRESTO-JST, Grant-in-Aid for Scientific Research (No.
16350074) from the Ministry of Education, Culture, Sports,
Science, and Technology, Japan, 21COE program “Creation of
Integrated EcoChemistry of Osaka University”, and by a grant
of the Asahi Glass Foundation.
Supporting Information Available: General experimental
information for X-ray crystal structure analyses, list of X-ray
crystallographic data for 1a, 1b, and (1a)2-TCNQ complex in CIF
format, and Ortep diagram and IR spectra. This material is available
free of charge via the Internet at http://pubs.acs.org.
(1b)2-TCNQ‚H2O Complex. Both a CH2Cl2 solution (130 mL)
of 1b (57 mg, 0.12 mmol) and a CH2Cl2 solution (20 mL) of TCNQ
(12 mg, 0.056 mmol) were combined in a 300-mL round-bottomed
JO060748L
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